generic_arg_infer: placeholder in signature err

compiler/rustc_typeck/src/astconv/mod.rs

@@ -6,7 +6,7 @@
 mod generics;
 
 use crate::bounds::Bounds;
-use crate::collect::PlaceholderHirTyCollector;
+use crate::collect::HirPlaceholderCollector;
 use crate::errors::{
     AmbiguousLifetimeBound, MultipleRelaxedDefaultBounds, TraitObjectDeclaredWithNoTraits,
     TypeofReservedKeywordUsed, ValueOfAssociatedStructAlreadySpecified,
@@ -2478,7 +2478,7 @@ pub fn ty_of_fn(
         debug!(?bound_vars);
 
         // We proactively collect all the inferred type params to emit a single error per fn def.
-        let mut visitor = PlaceholderHirTyCollector::default();
+        let mut visitor = HirPlaceholderCollector::default();
         for ty in decl.inputs {
             visitor.visit_ty(ty);
         }

compiler/rustc_typeck/src/collect.rs

@@ -112,9 +112,9 @@ pub struct ItemCtxt<'tcx> {
 ///////////////////////////////////////////////////////////////////////////
 
 #[derive(Default)]
-crate struct PlaceholderHirTyCollector(crate Vec<Span>);
+crate struct HirPlaceholderCollector(crate Vec<Span>);
 
-impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
+impl<'v> Visitor<'v> for HirPlaceholderCollector {
     fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
         if let hir::TyKind::Infer = t.kind {
             self.0.push(t.span);
@@ -131,6 +131,12 @@ fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
             _ => {}
         }
     }
+    fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
+        if let &hir::ArrayLen::Infer(_, span) = length {
+            self.0.push(span);
+        }
+        intravisit::walk_array_len(self, length)
+    }
 }
 
 struct CollectItemTypesVisitor<'tcx> {
@@ -175,7 +181,7 @@ struct CollectItemTypesVisitor<'tcx> {
         sugg.push((span, format!(", {}", type_name)));
     }
 
-    let mut err = bad_placeholder(tcx, "type", placeholder_types, kind);
+    let mut err = bad_placeholder(tcx, placeholder_types, kind);
 
     // Suggest, but only if it is not a function in const or static
     if suggest {
@@ -233,7 +239,7 @@ fn reject_placeholder_type_signatures_in_item<'tcx>(
         _ => return,
     };
 
-    let mut visitor = PlaceholderHirTyCollector::default();
+    let mut visitor = HirPlaceholderCollector::default();
     visitor.visit_item(item);
 
     placeholder_type_error(
@@ -311,7 +317,6 @@ fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
 
 fn bad_placeholder<'tcx>(
     tcx: TyCtxt<'tcx>,
-    placeholder_kind: &'static str,
     mut spans: Vec<Span>,
     kind: &'static str,
 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
@@ -322,8 +327,7 @@ fn bad_placeholder<'tcx>(
         tcx.sess,
         spans.clone(),
         E0121,
-        "the {} placeholder `_` is not allowed within types on item signatures for {}",
-        placeholder_kind,
+        "the placeholder `_` is not allowed within types on item signatures for {}",
         kind
     );
     for span in spans {
@@ -737,7 +741,7 @@ fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
                 match item.kind {
                     hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
                     hir::ForeignItemKind::Static(..) => {
-                        let mut visitor = PlaceholderHirTyCollector::default();
+                        let mut visitor = HirPlaceholderCollector::default();
                         visitor.visit_foreign_item(item);
                         placeholder_type_error(
                             tcx,
@@ -820,7 +824,7 @@ fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
                 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
                     // (#75889): Account for `const C: dyn Fn() -> _ = "";`
                     if let hir::TyKind::TraitObject(..) = ty.kind {
-                        let mut visitor = PlaceholderHirTyCollector::default();
+                        let mut visitor = HirPlaceholderCollector::default();
                         visitor.visit_item(it);
                         placeholder_type_error(
                             tcx,
@@ -856,7 +860,7 @@ fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
         hir::TraitItemKind::Const(..) => {
             tcx.ensure().type_of(trait_item_id.def_id);
             // Account for `const C: _;`.
-            let mut visitor = PlaceholderHirTyCollector::default();
+            let mut visitor = HirPlaceholderCollector::default();
             visitor.visit_trait_item(trait_item);
             placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
         }
@@ -865,7 +869,7 @@ fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
             tcx.ensure().item_bounds(trait_item_id.def_id);
             tcx.ensure().type_of(trait_item_id.def_id);
             // Account for `type T = _;`.
-            let mut visitor = PlaceholderHirTyCollector::default();
+            let mut visitor = HirPlaceholderCollector::default();
             visitor.visit_trait_item(trait_item);
             placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
         }
@@ -874,7 +878,7 @@ fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
             tcx.ensure().item_bounds(trait_item_id.def_id);
             // #74612: Visit and try to find bad placeholders
             // even if there is no concrete type.
-            let mut visitor = PlaceholderHirTyCollector::default();
+            let mut visitor = HirPlaceholderCollector::default();
             visitor.visit_trait_item(trait_item);
 
             placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
@@ -896,7 +900,7 @@ fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
         }
         hir::ImplItemKind::TyAlias(_) => {
             // Account for `type T = _;`
-            let mut visitor = PlaceholderHirTyCollector::default();
+            let mut visitor = HirPlaceholderCollector::default();
             visitor.visit_impl_item(impl_item);
 
             placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
@@ -1816,10 +1820,14 @@ fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
 /// use inference to provide suggestions for the appropriate type if possible.
 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
+    debug!(?ty);
     use hir::TyKind::*;
     match &ty.kind {
         Infer => true,
-        Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
+        Slice(ty) => is_suggestable_infer_ty(ty),
+        Array(ty, length) => {
+            is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
+        }
         Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
         Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
         OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
@@ -1871,9 +1879,9 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
                     });
                     let fn_sig = ty::Binder::dummy(fn_sig);
 
-                    let mut visitor = PlaceholderHirTyCollector::default();
+                    let mut visitor = HirPlaceholderCollector::default();
                     visitor.visit_ty(ty);
-                    let mut diag = bad_placeholder(tcx, "type", visitor.0, "return type");
+                    let mut diag = bad_placeholder(tcx, visitor.0, "return type");
                     let ret_ty = fn_sig.skip_binder().output();
                     if !ret_ty.references_error() {
                         if !ret_ty.is_closure() {

compiler/rustc_typeck/src/collect/type_of.rs

@@ -750,7 +750,7 @@ fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
             err.emit();
         }
         None => {
-            let mut diag = bad_placeholder(tcx, "type", vec![span], kind);
+            let mut diag = bad_placeholder(tcx, vec![span], kind);
 
             if !ty.references_error() {
                 let mut mk_nameable = MakeNameable::new(tcx);

src/test/ui/const-generics/generic_arg_infer/array-in-sig.rs

-// To avoid having to `or` gate `_` as an expr.
-#![feature(generic_arg_infer)]
-
-fn foo() -> [u8; _] {
-    //~^ ERROR the const placeholder `_` is not allowed within types on item signatures for generics
-    // FIXME(generic_arg_infer): this error message should say in the return type or sth like that.
-    [0; 3]
-}
-
-fn main() {
-    foo();
-}

src/test/ui/const-generics/generic_arg_infer/array-in-sig.stderr

-error[E0121]: the const placeholder `_` is not allowed within types on item signatures for generics
-  --> $DIR/array-in-sig.rs:4:18
-   |
-LL | fn foo() -> [u8; _] {
-   |                  ^ not allowed in type signatures
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0121`.

src/test/ui/const-generics/generic_arg_infer/in-signature.rs

+#![crate_type = "rlib"]
+#![feature(generic_arg_infer)]
+
+struct Foo<const N: usize>;
+struct Bar<T, const N: usize>(T);
+
+fn arr_fn() -> [u8; _] {
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+    [0; 3]
+}
+
+fn ty_fn() -> Bar<i32, _> {
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+    Bar::<i32, 3>(0)
+}
+
+fn ty_fn_mixed() -> Bar<_, _> {
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+    Bar::<i32, 3>(0)
+}
+
+const ARR_CT: [u8; _] = [0; 3];
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+static ARR_STATIC: [u8; _] = [0; 3];
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+const TY_CT: Bar<i32, _> = Bar::<i32, 3>(0);
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+static TY_STATIC: Bar<i32, _> = Bar::<i32, 3>(0);
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+const TY_CT_MIXED: Bar<_, _> = Bar::<i32, 3>(0);
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+static TY_STATIC_MIXED: Bar<_, _> = Bar::<i32, 3>(0);
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+trait ArrAssocConst {
+    const ARR: [u8; _];
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+}
+trait TyAssocConst {
+    const ARR: Bar<i32, _>;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+}
+trait TyAssocConstMixed {
+    const ARR: Bar<_, _>;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+}
+
+trait AssocTy {
+    type Assoc;
+}
+impl AssocTy for i8 {
+    type Assoc = [u8; _];
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
+}
+impl AssocTy for i16 {
+    type Assoc = Bar<i32, _>;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
+}
+impl AssocTy for i32 {
+    type Assoc = Bar<_, _>;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
+}

src/test/ui/const-generics/generic_arg_infer/in-signature.stderr

+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/in-signature.rs:7:21
+   |
+LL | fn arr_fn() -> [u8; _] {
+   |                -----^-
+   |                |    |
+   |                |    not allowed in type signatures
+   |                help: replace with the correct return type: `[u8; 3]`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/in-signature.rs:12:24
+   |
+LL | fn ty_fn() -> Bar<i32, _> {
+   |               ---------^-
+   |               |        |
+   |               |        not allowed in type signatures
+   |               help: replace with the correct return type: `Bar<i32, 3_usize>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/in-signature.rs:17:25
+   |
+LL | fn ty_fn_mixed() -> Bar<_, _> {
+   |                     ----^--^-
+   |                     |   |  |
+   |                     |   |  not allowed in type signatures
+   |                     |   not allowed in type signatures
+   |                     help: replace with the correct return type: `Bar<i32, 3_usize>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/in-signature.rs:22:15
+   |
+LL | const ARR_CT: [u8; _] = [0; 3];
+   |               ^^^^^^^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/in-signature.rs:24:20
+   |
+LL | static ARR_STATIC: [u8; _] = [0; 3];
+   |                    ^^^^^^^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/in-signature.rs:26:14
+   |
+LL | const TY_CT: Bar<i32, _> = Bar::<i32, 3>(0);
+   |              ^^^^^^^^^^^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace with the correct type: `Bar<i32, 3_usize>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/in-signature.rs:28:19
+   |
+LL | static TY_STATIC: Bar<i32, _> = Bar::<i32, 3>(0);
+   |                   ^^^^^^^^^^^
+   |                   |
+   |                   not allowed in type signatures
+   |                   help: replace with the correct type: `Bar<i32, 3_usize>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/in-signature.rs:30:20
+   |
+LL | const TY_CT_MIXED: Bar<_, _> = Bar::<i32, 3>(0);
+   |                    ^^^^^^^^^
+   |                    |
+   |                    not allowed in type signatures
+   |                    help: replace with the correct type: `Bar<i32, 3_usize>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/in-signature.rs:32:25
+   |
+LL | static TY_STATIC_MIXED: Bar<_, _> = Bar::<i32, 3>(0);
+   |                         ^^^^^^^^^
+   |                         |
+   |                         not allowed in type signatures
+   |                         help: replace with the correct type: `Bar<i32, 3_usize>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/in-signature.rs:35:21
+   |
+LL |     const ARR: [u8; _];
+   |                     ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/in-signature.rs:39:25
+   |
+LL |     const ARR: Bar<i32, _>;
+   |                         ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/in-signature.rs:43:20
+   |
+LL |     const ARR: Bar<_, _>;
+   |                    ^  ^ not allowed in type signatures
+   |                    |
+   |                    not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/in-signature.rs:51:23
+   |
+LL |     type Assoc = [u8; _];
+   |                       ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/in-signature.rs:55:27
+   |
+LL |     type Assoc = Bar<i32, _>;
+   |                           ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/in-signature.rs:59:22
+   |
+LL |     type Assoc = Bar<_, _>;
+   |                      ^  ^ not allowed in type signatures
+   |                      |
+   |                      not allowed in type signatures
+
+error: aborting due to 15 previous errors
+
+For more information about this error, try `rustc --explain E0121`.

src/test/ui/did_you_mean/bad-assoc-ty.rs

@@ -16,7 +16,7 @@
 
 type E = _::AssocTy;
 //~^ ERROR missing angle brackets in associated item path
-//~| ERROR the type placeholder `_` is not allowed within types on item signatures for type aliases
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for type aliases
 
 type F = &'static (u8)::AssocTy;
 //~^ ERROR missing angle brackets in associated item path
@@ -49,37 +49,37 @@
 
 trait K<A, B> {}
 fn foo<X: K<_, _>>(x: X) {}
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 fn bar<F>(_: F) where F: Fn() -> _ {}
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 fn baz<F: Fn() -> _>(_: F) {}
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 struct L<F>(F) where F: Fn() -> _;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for structs
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for structs
 struct M<F> where F: Fn() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for structs
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for structs
     a: F,
 }
 enum N<F> where F: Fn() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for enums
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for enums
     Foo(F),
 }
 
 union O<F> where F: Fn() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for unions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for unions
     foo: F,
 }
 
 trait P<F> where F: Fn() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for traits
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for traits
 }
 
 trait Q {
     fn foo<F>(_: F) where F: Fn() -> _ {}
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 }
 
 fn main() {}

src/test/ui/did_you_mean/bad-assoc-ty.stderr

@@ -81,7 +81,7 @@ error[E0223]: ambiguous associated type
 LL | type D = (u8, u8)::AssocTy;
    |          ^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(u8, u8) as Trait>::AssocTy`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for type aliases
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for type aliases
   --> $DIR/bad-assoc-ty.rs:17:10
    |
 LL | type E = _::AssocTy;
@@ -136,7 +136,7 @@ error[E0223]: ambiguous associated type
 LL | type I = ty!()::AssocTy;
    |          ^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:51:13
    |
 LL | fn foo<X: K<_, _>>(x: X) {}
@@ -149,7 +149,7 @@ help: use type parameters instead
 LL | fn foo<X: K<T, T>, T>(x: X) {}
    |             ~  ~ +++
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:54:34
    |
 LL | fn bar<F>(_: F) where F: Fn() -> _ {}
@@ -160,7 +160,7 @@ help: use type parameters instead
 LL | fn bar<F, T>(_: F) where F: Fn() -> T {}
    |         +++                         ~
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:57:19
    |
 LL | fn baz<F: Fn() -> _>(_: F) {}
@@ -171,7 +171,7 @@ help: use type parameters instead
 LL | fn baz<F: Fn() -> T, T>(_: F) {}
    |                   ~+++
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for structs
   --> $DIR/bad-assoc-ty.rs:60:33
    |
 LL | struct L<F>(F) where F: Fn() -> _;
@@ -182,7 +182,7 @@ help: use type parameters instead
 LL | struct L<F, T>(F) where F: Fn() -> T;
    |           +++                      ~
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for structs
   --> $DIR/bad-assoc-ty.rs:62:30
    |
 LL | struct M<F> where F: Fn() -> _ {
@@ -193,7 +193,7 @@ help: use type parameters instead
 LL | struct M<F, T> where F: Fn() -> T {
    |           +++                   ~
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for enums
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for enums
   --> $DIR/bad-assoc-ty.rs:66:28
    |
 LL | enum N<F> where F: Fn() -> _ {
@@ -204,7 +204,7 @@ help: use type parameters instead
 LL | enum N<F, T> where F: Fn() -> T {
    |         +++                   ~
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for unions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for unions
   --> $DIR/bad-assoc-ty.rs:71:29
    |
 LL | union O<F> where F: Fn() -> _ {
@@ -215,7 +215,7 @@ help: use type parameters instead
 LL | union O<F, T> where F: Fn() -> T {
    |          +++                   ~
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for traits
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for traits
   --> $DIR/bad-assoc-ty.rs:76:29
    |
 LL | trait P<F> where F: Fn() -> _ {
@@ -226,7 +226,7 @@ help: use type parameters instead
 LL | trait P<F, T> where F: Fn() -> T {
    |          +++                   ~
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:81:38
    |
 LL |     fn foo<F>(_: F) where F: Fn() -> _ {}

src/test/ui/error-codes/E0121.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/E0121.rs:1:13
    |
 LL | fn foo() -> _ { 5 }
@@ -7,7 +7,7 @@ LL | fn foo() -> _ { 5 }
    |             not allowed in type signatures
    |             help: replace with the correct return type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/E0121.rs:3:13
    |
 LL | static BAR: _ = "test";

src/test/ui/fn/issue-80179.rs

@@ -8,7 +8,7 @@ fn returns_i32() -> i32 {
 }
 
 fn returns_fn_ptr() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types [E0121]
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types [E0121]
 //~| NOTE not allowed in type signatures
 //~| HELP replace with the correct return type
 //~| SUGGESTION fn() -> i32
@@ -16,7 +16,7 @@ fn returns_fn_ptr() -> _ {
 }
 
 fn returns_closure() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types [E0121]
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types [E0121]
 //~| NOTE not allowed in type signatures
 //~| HELP consider using an `Fn`, `FnMut`, or `FnOnce` trait bound
 //~| NOTE for more information on `Fn` traits and closure types, see

src/test/ui/fn/issue-80179.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80179.rs:10:24
    |
 LL | fn returns_fn_ptr() -> _ {
@@ -7,7 +7,7 @@ LL | fn returns_fn_ptr() -> _ {
    |                        not allowed in type signatures
    |                        help: replace with the correct return type: `fn() -> i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80179.rs:18:25
    |
 LL | fn returns_closure() -> _ {

src/test/ui/issues/issue-69396-const-no-type-in-macro.rs

@@ -4,7 +4,7 @@
             const A = "A".$fn();
             //~^ ERROR the name `A` is defined multiple times
             //~| ERROR missing type for `const` item
-            //~| ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+            //~| ERROR the placeholder `_` is not allowed within types on item signatures for constants
         )*
     }
 }

src/test/ui/issues/issue-69396-const-no-type-in-macro.stderr

@@ -30,7 +30,7 @@ LL | | }
    |
    = note: this error originates in the macro `suite` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/issue-69396-const-no-type-in-macro.rs:4:19
    |
 LL |               const A = "A".$fn();

src/test/ui/self/self-infer.rs

 struct S;
 
 impl S {
-    fn f(self: _) {} //~ERROR the type placeholder `_` is not allowed within types on item signatures for functions
-    fn g(self: &_) {} //~ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    fn f(self: _) {} //~ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    fn g(self: &_) {} //~ERROR the placeholder `_` is not allowed within types on item signatures for functions
 }
 
 fn main() {}

src/test/ui/self/self-infer.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/self-infer.rs:4:16
    |
 LL |     fn f(self: _) {}
@@ -9,7 +9,7 @@ help: use type parameters instead
 LL |     fn f<T>(self: T) {}
    |         +++       ~
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/self-infer.rs:5:17
    |
 LL |     fn g(self: &_) {}

src/test/ui/suggestions/unnamable-types.rs

@@ -8,14 +8,14 @@
 //~| HELP: provide a type for the constant
 
 static B: _ = "abc";
-//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for static variables
+//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for static variables
 //~| NOTE: not allowed in type signatures
 //~| HELP: replace with the correct type
 
 
 // FIXME: this should also suggest a function pointer, as the closure is non-capturing
 const C: _ = || 42;
-//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for constants
+//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for constants
 //~| NOTE: not allowed in type signatures
 //~| NOTE: however, the inferred type
 

src/test/ui/suggestions/unnamable-types.stderr

@@ -4,7 +4,7 @@ error: missing type for `const` item
 LL | const A = 5;
    |       ^ help: provide a type for the constant: `A: i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/unnamable-types.rs:10:11
    |
 LL | static B: _ = "abc";
@@ -13,7 +13,7 @@ LL | static B: _ = "abc";
    |           not allowed in type signatures
    |           help: replace with the correct type: `&str`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/unnamable-types.rs:17:10
    |
 LL | const C: _ = || 42;

src/test/ui/type-alias-impl-trait/issue-77179.rs

@@ -5,7 +5,7 @@
 type Pointer<T> = impl std::ops::Deref<Target=T>;
 
 fn test() -> Pointer<_> {
-    //~^ ERROR: the type placeholder `_` is not allowed within types
+    //~^ ERROR: the placeholder `_` is not allowed within types
     Box::new(1)
 }
 

src/test/ui/type-alias-impl-trait/issue-77179.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-77179.rs:7:22
    |
 LL | fn test() -> Pointer<_> {

src/test/ui/typeck/issue-74086.rs

 fn main() {
     static BUG: fn(_) -> u8 = |_| 8;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions [E0121]
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions [E0121]
 }

src/test/ui/typeck/issue-74086.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/issue-74086.rs:2:20
    |
 LL |     static BUG: fn(_) -> u8 = |_| 8;

src/test/ui/typeck/issue-75883.rs

@@ -5,7 +5,7 @@ pub struct UI {}
 impl UI {
     pub fn run() -> Result<_> {
         //~^ ERROR: this enum takes 2 generic arguments but 1 generic argument was supplied
-        //~| ERROR: the type placeholder `_` is not allowed within types on item signatures for return types
+        //~| ERROR: the placeholder `_` is not allowed within types on item signatures for return types
         let mut ui = UI {};
         ui.interact();
 
@@ -14,7 +14,7 @@ pub fn run() -> Result<_> {
 
     pub fn interact(&mut self) -> Result<_> {
         //~^ ERROR: this enum takes 2 generic arguments but 1 generic argument was supplied
-        //~| ERROR: the type placeholder `_` is not allowed within types on item signatures for return types
+        //~| ERROR: the placeholder `_` is not allowed within types on item signatures for return types
         unimplemented!();
     }
 }

src/test/ui/typeck/issue-75883.stderr

@@ -34,13 +34,13 @@ help: add missing generic argument
 LL |     pub fn interact(&mut self) -> Result<_, E> {
    |                                           +++
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-75883.rs:15:42
    |
 LL |     pub fn interact(&mut self) -> Result<_> {
    |                                          ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-75883.rs:6:28
    |
 LL |     pub fn run() -> Result<_> {

src/test/ui/typeck/issue-75889.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constant items
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constant items
   --> $DIR/issue-75889.rs:3:24
    |
 LL | const FOO: dyn Fn() -> _ = "";
    |                        ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static items
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static items
   --> $DIR/issue-75889.rs:4:25
    |
 LL | static BOO: dyn Fn() -> _ = "";

src/test/ui/typeck/issue-80779.rs

@@ -3,11 +3,11 @@
 pub struct T<'a>(&'a str);
 
 pub fn f<'a>(val: T<'a>) -> _ {
-    //~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR: the placeholder `_` is not allowed within types on item signatures for return types
     g(val)
 }
 
 pub fn g(_: T<'static>) -> _ {}
-//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for return types
+//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for return types
 
 fn main() {}

src/test/ui/typeck/issue-80779.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80779.rs:10:28
    |
 LL | pub fn g(_: T<'static>) -> _ {}
@@ -7,7 +7,7 @@ LL | pub fn g(_: T<'static>) -> _ {}
    |                            not allowed in type signatures
    |                            help: replace with the correct return type: `()`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80779.rs:5:29
    |
 LL | pub fn f<'a>(val: T<'a>) -> _ {

src/test/ui/typeck/issue-81885.rs

 const TEST4: fn() -> _ = 42;
-                  //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+                  //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 fn main() {
     const TEST5: fn() -> _ = 42;
-                      //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+                      //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 }

src/test/ui/typeck/issue-81885.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/issue-81885.rs:1:22
    |
 LL | const TEST4: fn() -> _ = 42;
    |                      ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/issue-81885.rs:5:26
    |
 LL |     const TEST5: fn() -> _ = 42;

src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/issue-83621-placeholder-static-in-extern.rs:4:15
    |
 LL |     static x: _;

src/test/ui/typeck/issue-91450-inner-ty-error.rs

@@ -2,6 +2,6 @@
 // This test ensures that the compiler does not suggest `Foo<[type error]>` in diagnostic messages.
 
 fn foo() -> Option<_> {} //~ ERROR: [E0308]
-//~^ ERROR: the type placeholder `_` is not allowed
+//~^ ERROR: the placeholder `_` is not allowed
 
 fn main() {}

src/test/ui/typeck/issue-91450-inner-ty-error.stderr

@@ -9,7 +9,7 @@ LL | fn foo() -> Option<_> {}
    = note:   expected enum `Option<_>`
            found unit type `()`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-91450-inner-ty-error.rs:4:20
    |
 LL | fn foo() -> Option<_> {}

src/test/ui/typeck/type-placeholder-fn-in-const.rs

@@ -2,13 +2,13 @@
 
 trait Test {
     const TEST: fn() -> _;
-    //~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for functions [E0121]
-    //~| ERROR: the type placeholder `_` is not allowed within types on item signatures for constants [E0121]
+    //~^ ERROR: the placeholder `_` is not allowed within types on item signatures for functions [E0121]
+    //~| ERROR: the placeholder `_` is not allowed within types on item signatures for constants [E0121]
 }
 
 impl Test for MyStruct {
     const TEST: fn() -> _ = 42;
-    //~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for functions [E0121]
+    //~^ ERROR: the placeholder `_` is not allowed within types on item signatures for functions [E0121]
 }
 
 fn main() {}

src/test/ui/typeck/type-placeholder-fn-in-const.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/type-placeholder-fn-in-const.rs:4:25
    |
 LL |     const TEST: fn() -> _;
    |                         ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/type-placeholder-fn-in-const.rs:4:25
    |
 LL |     const TEST: fn() -> _;
    |                         ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/type-placeholder-fn-in-const.rs:10:25
    |
 LL |     const TEST: fn() -> _ = 42;

src/test/ui/typeck/typeck_type_placeholder_item.rs

@@ -5,67 +5,67 @@
 // inference by using the `_` type placeholder.
 
 fn test() -> _ { 5 }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
 fn test2() -> (_, _) { (5, 5) }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
 static TEST3: _ = "test";
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
 
 static TEST4: _ = 145;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
 
 static TEST5: (_, _) = (1, 2);
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
 
 fn test6(_: _) { }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 fn test6_b<T>(_: _, _: T) { }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 fn test7(x: _) { let _x: usize = x; }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 fn test8(_f: fn() -> _) { }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
-//~^^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+//~^^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 struct Test9;
 
 impl Test9 {
     fn test9(&self) -> _ { () }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
     fn test10(&self, _x : _) { }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 }
 
 fn test11(x: &usize) -> &_ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
     &x
 }
 
 unsafe fn test12(x: *const usize) -> *const *const _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
     &x
 }
 
 impl Clone for Test9 {
     fn clone(&self) -> _ { Test9 }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
     fn clone_from(&mut self, other: _) { *self = Test9; }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 }
 
 struct Test10 {
     a: _,
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for structs
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for structs
     b: (_, _),
 }
 
@@ -73,94 +73,94 @@ pub fn main() {
     static A = 42;
     //~^ ERROR missing type for `static` item
     static B: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
     static C: Option<_> = Some(42);
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
     fn fn_test() -> _ { 5 }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
     fn fn_test2() -> (_, _) { (5, 5) }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
     static FN_TEST3: _ = "test";
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
 
     static FN_TEST4: _ = 145;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
 
     static FN_TEST5: (_, _) = (1, 2);
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
 
     fn fn_test6(_: _) { }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
     fn fn_test7(x: _) { let _x: usize = x; }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
     fn fn_test8(_f: fn() -> _) { }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
-    //~^^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    //~^^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
     struct FnTest9;
 
     impl FnTest9 {
         fn fn_test9(&self) -> _ { () }
-        //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
         fn fn_test10(&self, _x : _) { }
-        //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
     }
 
     impl Clone for FnTest9 {
         fn clone(&self) -> _ { FnTest9 }
-        //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
         fn clone_from(&mut self, other: _) { *self = FnTest9; }
-        //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
     }
 
     struct FnTest10 {
         a: _,
-        //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for structs
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for structs
         b: (_, _),
     }
 
     fn fn_test11(_: _) -> (_, _) { panic!() }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
     //~| ERROR type annotations needed
 
     fn fn_test12(x: i32) -> (_, _) { (x, x) }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
     fn fn_test13(x: _) -> (i32, _) { (x, x) }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 }
 
 trait T {
     fn method_test1(&self, x: _);
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
     fn method_test2(&self, x: _) -> _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
     fn method_test3(&self) -> _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
     fn assoc_fn_test1(x: _);
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
     fn assoc_fn_test2(x: _) -> _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
     fn assoc_fn_test3() -> _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 }
 
 struct BadStruct<_>(_);
 //~^ ERROR expected identifier, found reserved identifier `_`
-//~| ERROR the type placeholder `_` is not allowed within types on item signatures for structs
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for structs
 trait BadTrait<_> {}
 //~^ ERROR expected identifier, found reserved identifier `_`
 impl BadTrait<_> for BadStruct<_> {}
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for implementations
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for implementations
 
 fn impl_trait() -> impl BadTrait<_> {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for opaque types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for opaque types
     unimplemented!()
 }
 
@@ -168,19 +168,19 @@ fn impl_trait() -> impl BadTrait<_> {
 //~^ ERROR expected identifier, found reserved identifier `_`
 //~| ERROR expected identifier, found reserved identifier `_`
 //~| ERROR the name `_` is already used
-//~| ERROR the type placeholder `_` is not allowed within types on item signatures for structs
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for structs
 struct BadStruct2<_, T>(_, T);
 //~^ ERROR expected identifier, found reserved identifier `_`
-//~| ERROR the type placeholder `_` is not allowed within types on item signatures for structs
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for structs
 
 type X = Box<_>;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for type aliases
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for type aliases
 
 struct Struct;
 trait Trait<T> {}
 impl Trait<usize> for Struct {}
 type Y = impl Trait<_>;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for opaque types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for opaque types
 fn foo() -> Y {
     Struct
 }
@@ -188,25 +188,25 @@ fn foo() -> Y {
 trait Qux {
     type A;
     type B = _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for associated types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
     const C: _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
     const D: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
     // type E: _; // FIXME: make the parser propagate the existence of `B`
     type F: std::ops::Fn(_);
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for associated types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
 }
 impl Qux for Struct {
     type A = _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for associated types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
     type B = _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for associated types
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
     const C: _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
     //~| ERROR associated constant in `impl` without body
     const D: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
 }
 
 fn map<T>(_: fn() -> Option<&'static T>) -> Option<T> {
@@ -214,9 +214,9 @@ fn map<T>(_: fn() -> Option<&'static T>) -> Option<T> {
 }
 
 fn value() -> Option<&'static _> {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
     Option::<&'static u8>::None
 }
 
 const _: Option<_> = map(value);
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants

src/test/ui/typeck/typeck_type_placeholder_item_help.rs

@@ -2,27 +2,27 @@
 // using the `_` type placeholder.
 
 fn test1() -> _ { Some(42) }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
 
 const TEST2: _ = 42u32;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
 
 const TEST3: _ = Some(42);
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
 
 const TEST4: fn() -> _ = 42;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
 
 trait Test5 {
     const TEST5: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
 }
 
 struct Test6;
 
 impl Test6 {
     const TEST6: _ = 13;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
 }
 
 pub fn main() {

src/test/ui/typeck/typeck_type_placeholder_item_help.stderr

-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item_help.rs:4:15
    |
 LL | fn test1() -> _ { Some(42) }
@@ -7,7 +7,7 @@ LL | fn test1() -> _ { Some(42) }
    |               not allowed in type signatures
    |               help: replace with the correct return type: `Option<i32>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:7:14
    |
 LL | const TEST2: _ = 42u32;
@@ -16,7 +16,7 @@ LL | const TEST2: _ = 42u32;
    |              not allowed in type signatures
    |              help: replace with the correct type: `u32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:10:14
    |
 LL | const TEST3: _ = Some(42);
@@ -25,13 +25,13 @@ LL | const TEST3: _ = Some(42);
    |              not allowed in type signatures
    |              help: replace with the correct type: `Option<i32>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item_help.rs:13:22
    |
 LL | const TEST4: fn() -> _ = 42;
    |                      ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:17:18
    |
 LL |     const TEST5: _ = 42;
@@ -40,7 +40,7 @@ LL |     const TEST5: _ = 42;
    |                  not allowed in type signatures
    |                  help: replace with the correct type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:24:18
    |
 LL |     const TEST6: _ = 13;